Not Applicable
Not Applicable
This invention relates to implant assemblies for use in stabilizing bone members to treat patients with ruptured or degenerated intervertebral bone discs and to replace vertebrae or individual bone bodies damaged by fracture, tumor or degenerative processes. Specifically, the invention relates to dynamized vertebral or individual bone implants and methods of implanting them to form a support in the spinal column or bone column and to promote fusion, healing, and bone growth in the human spine or bone column, incorporating an elongated member such as a plate.
When surgery is needed, the discs are removed and replaced with grafts that will heal or fuse with the vertebra or individual bones. This implanted graft provides realignment and stabilization while healing takes place. Those surgeries that use implanted stabilizers, along with a graft are more successful than those that do not use a stabilizer. Surgeries that maintain compression between the vertebra or individual bones during healing are the most successful.
Devices that support all of the vertebra or individual bone""s force leaving no force on the intervertebral or individual bone""s graft are called xe2x80x9cstress shieldingxe2x80x9d devices. Devices that support or share a portion of the spinal load in parallel with the graft are called xe2x80x9cload sharingxe2x80x9d devices. Devices that allow axial subsidence of the implant and support most of the load on the individual bone grafts are referred to as providing xe2x80x9cdynamizedxe2x80x9d action.
The present invention allows the surgeon to select any of these three conditions at the time of surgery, by selecting the bone screw nut and positioning the stop Lock clamp. The present patent will restrict distraction, lateral translation, and rotational shear, reducing the stretching rupture and shear tearing of the forming nutrient blood vessels while allowing compression during the healing process.
The present patent relates to a spinal stabilizing device, and a method of implanting it on the posterior, or lateral side of the human spine or bone column. This device includes a rectangular shaped plate to allow axial subsiding motion without rotation or shear translation. The plate is for placement adjacent to and along the spinal or bone column, and having a longitudinal axis. The plate includes an open slot substantially parallel to the plate axis extending substantially the entire longitudinal dimension of the plate, leaving the plate ends the same thickness as the plate rails. The plate is raised above the individual bones by the thickness of a bone screw driving portion and the thickness of a plate guide. The stabilizer further includes a plate guide with two tubes attached to the plate guide and extending perpendicular to the plane of the plate guide and having inner diameters which slidably engage machine screws and outer diameters which will slidably engage the plate slot. The plate guide also including an xe2x80x9cLxe2x80x9d shaped extension, referred to as the outrigger arm extending perpendicular to and in the plane of the plate guide anteriorly, for placement of an anterior bone screw which is fixed to the plate guide through a locking means. This system also includes a bone screw having a bone threaded portion which engages the bone, a driving portion, and a machine thread stud portion extending through the plate guide tubes, so that the screw""s driving portion abuts the vertebra or individual bones, and the machine thread portion engages the tubes and protrudes above the tubes. Also provided are two different nuts with a threaded hole extending through the body portion for threaded engagement with the machine threaded portion and a flange substantially concentric with the nut""s thread. One nut includes an undercut and is referred to as a clamp nut, the second nut, which does not have an undercut, is referred to as a sliding nut. If a sliding nut is used it will clamp against the tube, leaving clearance between the plate and the plate guide allowing for dynamized motion. If a clamp nut is used, the nut will not contact the Tube, but will clamp the plate to the plate guide for rigid clamping. At the time of implantation the device is adapted to either rigidly fix the vertebra or individual bones or to allow selected axial subsiding action. Stop Lock clamps are provided to control the displacement of the plate with respect to the plate guides and to add torsional rigidity to the implant and improve pullout resistance by virtue of its orientation relative to the Posterior Bone Screws.